The present invention generally relates to methods and apparatus for making and filling bags having a block bottom and a pillow top.
In the automated manufacture of plastic reclosable packages or bags, it is known to feed a zipper assembly comprising interlocked zipper strips (formed by extrusion) to a position adjacent and transverse to a web of thermoplastic film and then attach one strip of the zipper assembly to the web by means of heat sealing, prior to the web entering a vertical form-fill-seal (VFFS) machine. The zipper assemblies are attached at spaced intervals along the thermoplastic sheet, one zipper assembly being attached to each section of film respectively corresponding to an individual package or bag. The zipper assembly consists of two interlocking zipper strips that typically lie inside the mouth of the package.
In accordance with one known method, zipper assemblies are automatically fed to a zipper application station in the form of a tape that is unwound from a spool. The tape comprises a continuous length of interlocked fastener strips. The continuous tape is fed to a cutting device that cuts the tape at regular lengths to form an individual zipper. Each individual zipper is then attached at spaced intervals to the thermoplastic bag making film by heat sealing or other suitable means. The zipper-carrying film is then pulled through the VFFS machine, which forms, fills and seals successive packages.
There is a need for improved methods and apparatus for automated manufacture of bags having a pillow-style top, a block-shaped bottom, and side gussets extending upward from the bottom but not reaching the top. The method should enable the manufacture of block bottom, pillow top bags with or without a reclosable feature (e.g., a zipper)